Cholesterol Synthesis Flashcards
Where is cholesterol synthesized?
In the liver
Cholesterol is a non-polar molecule synthesized primarily in the liver.
What are the functions of cholesterol?
- Structural component of membranes
- Precursor of bile acids
- Precursor of steroid hormones
- Precursor of vitamin D
What is the building block for cholesterol synthesis?
Acetyl CoA
Eighteen molecules of Acetyl CoA are required for the synthesis of one molecule of cholesterol.
What is the first committed step in cholesterol synthesis?
Formation of Mevalonate from HMG-CoA
This step involves the enzyme HMG-CoA reductase.
List the four stages of cholesterol synthesis.
- Mevalonate
- Activated Isoprene
- Squalene
- Cholesterol
What happens to excess cholesterol in the body?
Converted to bile acids and stored in the gallbladder
How is cholesterol transported in the body?
- VLDL - transports cholesterol from liver
- HDL - picks up cholesterol from blood and tissues
- LDL - transports cholesterol from liver to tissues
What effect does high cholesterol have on the transcription of the gene for HMG-CoA reductase?
Transcription slows down
What stimulates the degradation of HMG-CoA reductase?
Elevated levels of cholesterol
What happens when cholesterol levels are low in the body?
Stimulated processes for cholesterol synthesis and uptake
What condition is characterized by high cholesterol levels in the blood?
Familial Hypercholesterolemia
What causes Familial Hypercholesterolemia?
Defective LDL receptors
Fill in the blank: Cholesterol is exported in _______.
LDL’s
True or False: LDL transports cholesterol back to the liver.
False
